A pertinent aircraft passenger seat, described in DE 199 44 620, has individual seat components, including a leg rest and a backrest. These seat components can be moved by actuating means which can be triggered by a hand-operated actuating means for adjusting the seat to the requirements of the seat occupant. Hand levers for the seat parts are modeled to the contours of these seat parts as an element of the actuating means, and are combined in one operating part for adjusting the aircraft passenger seat for meaningful adjustment for the seat parts.
In all known tilt adjustment means for seat parts, such as a backrest or leg rest, depending on the actuating and tilt adjustment means used at the time, obstacles can arise since generally the actuating means engages only one point of the backrest and/or leg rest. This single point engagement leads to twisting or torsion of the other seat part to be adjusted in its tilt. Even with minor twisting or torsion, a uniform swivelling motion cannot be achieved with a good feeling of the body for the seat occupant. Also, depending on the adjustment structure being used, in case of a crash, unilateral loading of the actuating means, especially in the form of a servo-drive, occurs. The activating means are often not able to accommodate the forces which suddenly occur.
DE-A-33 35 486 A1 discloses a device for adjusting the height and the tilt of the backrest of the seat, especially of a motor vehicle seat. For selective adjustment of the tilt of a backrest or the height of the entire seat by a single drive spindle, the drive spindle has two spindle parts which each bear a mating non-rotatable bevel wheel to interact with a bevel wheel on the spindles of individual adjustment mechanisms. They are connected non-rotatably only in a certain relative axial position by way of gear rings. In this position, only one mating bevel wheel meshes with the assigned bevel wheel. In the other relative axial position of the two drive spindle parts, the two mating bevel wheels mesh with the assigned bevel wheels, but the non-rotatable connection between the two drive spindle parts is canceled. The known gear approach has a plurality of bevel wheels which fit into one another at a right angle so that the known approach takes up a relatively large amount of construction space on the respective vehicle seat and is accordingly heavy. Furthermore, the approach based on a plurality of individual components is structurally complex and expensive to produce.
DE-A-34 12 047 A1 discloses a generic device for adjusting the tilt of the backrest of a seat, especially for motor vehicles. The seat has a backrest frame with two laterally arranged rotary fittings driven by way of intermediate pinion gears by a drive shaft. The drive shaft is supported in the seat frame and is driven by a synchronous belt drive from a handwheel supported on the front end of the seat frame. As a result, a continuous shaft is not necessary in the backrest, and the handwheel for driving the seat back adjustment is located at a favorable site which is easy to reach. Since synchronous belt drives with their drive wheels and shafts are fundamentally subject to a certain slip behavior, there is no smooth and uniform triggering of the adjustment motion on the two lengthwise sides of the backrest, and obstacles in operation must be expected. Furthermore, the known and aforementioned approaches have the disadvantage that they are hardly suitable for reliably accommodating the peak loads which occur in the seat base structure in case of a crash, if it is used in the vehicle domain, especially in the aircraft domain.